[eric9610]

Originally Posted by edx1

I'm curious where you have read the x1 xDrive35i uses the same transmission as the 335d. Can you support this with documentation? Please do before accusing someone of posting misinformation.

According to owners here on bimmerfest, the 335d uses the ZF 6HP26 transmission which is similar to the ZF 6HP19TU, 6HP19Z and 6HP21 however the difference is primarily in the plates and as a consequence a reduction in the amount of torque each transmission can handle. The ZF 6HP26 can handle 443ftlb while the ZF 6HP21 is designed to handle 332ft-lb according to ZF here: http://apps01.zf.com/zf.productDataB...n_EN_2006s.pdf

Now the manual for the X1 reports the transmission as the ZF 6HP19TU which is to be an upgraded and second generation of the 295ft-lb max ZF 6HP19.

People have reported that on other BMW models that were listed as a ZF 6HP19TU the actual transmissions in the car had the embossing of 6HP21 on them. I haven't dug that deep into my X1 engine bay to verify nor has anyone else reported they have checked that I've seen, but as it stands right now the ZF 6HP21 is the most likely transmission in the x1 xDrive35i but there's a big * in saying this. The TU is suppose to stand for Technical Update and the term 6HP19Z has also been used to denote this improvement. It might be that BMW uses these two terms to denote something internally but we do know and I'll repeat, that the ZF 6HP21 was found in other BMW models where these two terms were used in documentation, just like we see in the X1 documentation.

The max torque reported in documentation by ZF for a 6HP21 is 450nm or 331.9 ft lbs, plain and simple.

There was speculation at one point that a transmission labelled ZF 6HP19TU could handle somewhere between that 450nm and the 600nm (443ft lbs) that the ZF 6HP26 can handle, as I gave in a range in my earlier post, but I have found no documentation or solid information anywhere what a ZF 6HP19TU transmission can handle.

There is also the question of what if an difference there between a true 6HP21 that handles 332ft lbs and the "6HP19TU in documentation yet the actual transmission in the car says 6HP21". I have a hard time believing there are 2 6HP21's with different torque ratings that go by the same part number... Thus I'm skeptical a transmission called 6HP19TU in documentation would be listed as being handle any more than 332ft lbs.

All this has been talked about before, googling 6hp19tu will give you plenty to read up on, including a discussion here on bimmerfest last year: http://www.bimmerfest.com/forums/sho...d.php?t=627364 post #14 in particular documentation here http://www.***********.com/showthrea...ence-Documents

But if you have time, please dig into your engine bay and let us know what part number is on your x1 xDrive35i... Is it the 6HP26 that's used in the 335d like you're saying or a different part number?

The facts are there is a Dinan tune available that puts out over 400lbft of tq and is covered by warranty is all i need to know. I don't think anyone here knows for sure what the true tq load our transmissions can handle but the fact a tuner who provides warranty coverage matching BMW factory says all i need to know. No engineer or manufacturer would ever design something so close to a failure threshold since there are so many variables. I like to call this common sense.